However, that would be just as good as it would be for Ruud, who is making his ATP Finals debut, as Djokovic rallied to take the first set to a tiebreak.
From then on, it looked like there would be only one winner.
The second set proved to be an entirely more one-sided affair, with Djokovic stamping his authority on the match, eventually winning within an hour and 30 minutes.
The win takes Djokovic to 39 career wins at the ATP Tour Finals, putting Ivan Lendl in a tie for second place. Roger Federer remains way ahead with a remarkable 59 wins.
Djokovic, who recently set a record seventh in the world rankings at the end of the year, has not won the ATP Finals title since 2015, despite being arguably the most dominant player on the track at the time.
The 34-year-old came closest to equaling Federer’s record of six ATP Finals titles in 2018, when he lost in the final to this year’s No. 3 seed Alexander Zverev.
While Djokovic and Ruud may be on the other side of their careers, the 22-year-old is already showing signs that he could be one of the vaunted next generation to carry the torch of tennis’s old guard.
Ruud won no fewer than five ATP titles in 2021, becoming the first Norwegian player to qualify for the prestigious year-end ATP Finals, in which the world’s top eight compete in a round robin format before he advances to a knockout stage.
Earlier this year, Ruud won three ATP titles in as many weeks, becoming the first man since Andy Murray in 2011 to achieve that feat.
The youngster showed impressive resilience against Djokovic on Monday, most notably with his serve in a brutal game to take the first set to a tiebreak, but he is still looking for his first hard-field win over a top 10 player.
Next up for Djokovic is the winner of Monday night’s match between Stefanos Tsitsipas and Andrey Rublev.